In a high current oxygen torch, electrode and nozzle life can be very short as compared with lower current processes. Nozzle life in a high current oxygen torch can be short due to the excessive heat load imparted to the nozzle tip. One method of reducing the heat load on a nozzle and increasing nozzle life is by venting a portion of plasma gas from before the nozzle bore. See, e.g., U.S. Pat. No. 5,317,126 entitled “Nozzle and Method of Operation for a Plasma Arc Torch” filed on Jan. 14, 1992, the contents of which are incorporated by reference in their entirety. Venting further helps constrict the arc by pinching the arc and cooling the nozzle. Vented plasma processes can achieve a more highly constricted arc, which can improve cut performance while extending nozzle life. Cooling a nozzle wall at the nozzle exit orifice can produce a thin boundary layer of cooled gas, which can protect the nozzle and pinch the arc (e.g., cause the arc to contract by this energy drain from its boundary). Cooling can also aid in controlling double arcing and gouging of the nozzle orifice (i.e. when the arc contacts the wall.)
Electrode life can be extended by improved cooling of the hafnium emitter, e.g., using Hypertherm's Cool Core design. See, e.g., U.S. Pat. No. 6,130,399 entitled “Electrode for a Plasma Arc Torch Having an Improved Insert Configuration” filed on Jul. 20, 1998, the contents of which are incorporated by reference in their entirety). However, electrode life can still be short, especially when the plasma gas swirl injection point is far upstream from the electrode face (e.g., due to a large plasma plenum). Electrode life can be improved as the swirl injection location is moved closer to the electrode face. A plasma arc torch can have a swirl injection point that is close to an electrode face (e.g., resulting in a reduced plenum). For example, the HT4400 400A O2 plasma process has a swirl ring design has a “closer” swirl injection location. Moving the swirl injection location closer to the electrode face can enhance electrode life in a high current torch because it reduces the amount of emitter wear during operation of the torch. A long swirl ring can be used to accomplish a swirl injection point close to the electrode face, extending electrode life.